An exhaust gas-purifying catalyst includes a substrate, and a catalytic layer facing the substrate and including a precious metal, alumina, an oxygen storage material, and a sulfate of an alkaline-earth metal having an average particle diameter falling within a range of 0.01 to 0.70 μm, the average particle diameter being obtained by observation using a scanning electron microscope. Another exhaust gas-purifying catalyst includes a substrate, and a catalytic layer formed on the substrate using slurry containing a precious metal, alumina, an oxygen storage material, and a sulfate of an alkaline-earth metal having an average particle diameter falling within a range of 0.01 to 0.70 μm, the average particle diameter being obtained by observation using a scanning electron microscope.

Exhaust gas purifying catalyst

To provide an exhaust gas purifying system capable of forcibly regenerating DPF by efficiently raising the temperature of exhaust gas even when an exhaust gas temperature is very low at the time of low load and low engine speed such as an idling operation. In an exhaust purifying system (1) having an exhaust throttling valve (31) and a DPF (3) in an exhaust passage and having regeneration control means (P1) for regenerating the DPF (3), the regeneration control means (P1) is provided with an exhaust gas temperature detection means (P22), a fuel injection control means (P11), and an exhaust throttling control means (P12) and includes regeneration control for performing the exhaust gas temperature raising control through the multistage delay injection by the fuel injection control means (P11) and through the exhaust throttling of the exhaust throttling valve (31).

Exhaust gas purifying system

According to the present invention, an exhaust gas purifying catalyst is provided. The catalyst comprises a porous silica support comprising silica having a pore structure, and a perovskite-type composite metal oxide particle supported in the pore structure of the porous silica support. Further, the peak attributable to the space between silica primary particles is in the range of 3 to 100 nm in the pore distribution of the porous silica support.

A layered, three-way conversion catalyst having the capability of simultaneously catalyzing the oxidation of hydrocarbons and carbon monoxide and the reduction of nitrogen oxides is disclosed. Methods of making and using the same are also provided. In one or more embodiments, the catalyst comprises three layers of catalytic material in conjunction with a carrier. A first layer comprises a platinum component on a first support; a second layer comprises a rhodium component on a second support; and a third layer comprises a palladium component and a third support. The palladium, rhodium, and/or platinum can independently be deposited on a support of high surface area refractory metal oxide, or of an oxygen storage component, or both.

Multilayered Catalyst Compositions

The invention relates to a first catalyst for purifying an exhaust gas. The first catalyst has a substrate and a catalytic coating formed thereon. This catalytic coating has first and second grains. The first grain includes a porous carrier supporting thereon at least one of palladium and rhodium. The second grain includes a double oxide supporting thereon at least one of platinum and palladium. This double oxide is represented by a formula of (La1-x Ax)1-α BO.sub.δ where A is at least one element selected from barium, potassium and cesium, B is at least one of iron, cobalt, nickel and manganese, 0<X<1, 0<α<0.2, and δ is a number such that a net electric charge of the first double oxide becomes zero. The invention further relates to a second catalyst similar to the first catalyst. The first grain of the second catalyst includes a porous carrier supporting thereon at least one of platinum, palladium, rhodium and iridium. The second grain of the second catalyst includes a double oxide represented by a formula of (La1-x Ax)1-α BZr.sub.β O.sub.δ where A, B, x, α and δ are defined as above and 0<β<1. The first and second catalysts are each improved in NOx absorption capability and capable of purifying NOx contained in an oxygen rich exhaust gas, even after the passage of an exhaust gas of high temperature for a long time through these catalysts.

Catalyst for purifying oxygen rich exhaust gas

A catalyst for purifying exhaust gas from an automotive internal combustion engine. The catalyst comprises a monolithic carrier which is coated with a catalyst component carrying layer which includes rhodium and a zirconium oxide. The zirconium oxide contains at least one element selected from the group consisting of magnesium, calcium, strontium, barium, yttrium and lanthanum. The zirconium oxide in the catalyst component carrying layer has a composition represented by a general formula of X! a Zr b O c where X is at least one element selected from the group consisting of magnesium, calcium, strontium, barium, yttrium and lanthanum; and a, b and c indicate ratios in number of atoms, in which a is within a range of from 0.01 to 0.6 on the assumption of b being 1.0, and c is a number of oxygen atom which satisfies valence of respective elements.

Shinji Yamamoto

Papers

Catalyst for purifying exhaust gas and method of producing same